1. Technical Field
Example embodiments of the present invention relate in general to a wireless communication system, and more specifically to a method of transmitting and receiving a control channel in a wireless communication system.
2. Related Art
A data transmission rate in wireless communication systems and wired communication systems has recently become very high. In line with this trend, the 3rd generation project partnership long term evolution (3GPP LTE) system and the LTE-advanced system are presently undergoing standardization.
In the 3GPP LTE system, downlink transmission is based on orthogonal frequency division multiplexing (OFDM), and uplink transmission is based on single frequency-frequency division multiple access (SC-FDMA).
That is, the 3GPP system uses time-frequency resources as fundamental physical resources, and each resource element corresponds to one OFDM subcarrier during one OFDM symbol period. Also, downlink subcarriers are grouped into a plurality of resource blocks in a frequency domain, and each of the resource blocks consists of twelve successive subcarriers.
In the 3GPP LTE system, the physical downlink shared channel (PDSCH) is used as a physical channel for transmitting downlink unicast data, and the physical uplink shared channel (PUSCH) is used as a downlink physical data channel for transmitting uplink data. Also, the physical downlink control channel (PDCCH) is used as a downlink physical control channel for transmitting downlink control information, such as scheduling necessary for receiving the PDSCH, and scheduling approval for transmission in the PUSCH. The downlink physical data channel and the downlink physical control channel are mapped in units of subframes comprising time-frequency resources.
When a data channel and a control channel are multiplexed in one subframe, a base station provides start position information of the data channel in a time domain, for which an efficient method is required.
Moreover, when the enhanced PDCCH (ePDCCH) allocated to a data channel region of a subframe is introduced, an efficient control channel transmission method is necessary for both an enhanced system capable of transmitting/receiving the ePDCCH and a legacy system incapable of transmitting/receiving the ePDCCH.